In her first network interview since the assassination attempt on former President Donald Trump, U.S. Secret Service Director Kimberly Cheatle offered insight into the logistics surrounding the deadly shooting Saturday.

"It was unacceptable," she said in an interview Monday with ABC News Chief Justice Correspondent Pierre Thomas. "And it's something that shouldn't happen again."

Cheatle said that local authorities were tasked with securing the building where the alleged shooter fired the shots before being taken out by a Secret Service sniper, and confirmed that local police were present inside the building while the shooter was on the roof.

"In this particular instance, we did share support for that particular site and that the Secret Service was responsible for the inner perimeter," Cheatle said. "And then we sought assistance from our local counterparts for the outer perimeter. There was local police in that building -- there was local police in the area that were responsible for the outer perimeter of the building."

She is expected to testify before the GOP-led House Oversight Committee next Monday, July 22.

-ABC News' Julia Reinstein

Former President Donald Trump shared an update with ABC News' Jonathan Karl on how his right ear is recovering and said the assassination attempt at his campaign rally Saturday had "impact."

When asked if the close call to the bullet striking his head "changed him," Trump said, "I don’t like to think about that, but, yes, I think has an impact."

Trump said his ear is doing fine and that he hopes the bandage will be off by the time he speaks on Thursday at the Republican National Convention.

Homeland Security Secretary Alejandro Mayorkas announced an independent review of the shooting and said it will be launched in "days."

"We are, indeed, in the process of selecting who will lead the independent review. The findings indeed will be made public," he said. "It is very important that we achieve transparency so that the American people have confidence in the work of the review and its findings and recommendations. And we need to move with swiftness and urgency, because this is a security imperative."

Mayorkas said he was committed to going "externally of the government" so that "no question of its independence can be raised."

Mayorkas told reporters he has "100% confidence" in Secret Service Director Kimberly Cheatle, and White House press secretary Karine Jean-Pierre said President Joe Biden also has confidence in the director.

Biden told reporters Monday that he has faith in his own Secret Service detail and faith in the agency.

-ABC News’ Justin Ryan Gomez

Secret Service protection has been increased for former President Donald Trump, Homeland Security Secretary Alejandro Mayorkas said.

The enhancement is "based on the evolving nature of threats to the former president and his imminent shift from presumptive nominee to nominee," Mayorkas said. "This includes enhancements related to securing the former president during the Republican National Convention this week. I cannot discuss specifics ... as they involve sensitive tactics and procedures. I can say, however, that personnel and other protective resources, technology and capabilities have been added."

"Adjustments" have also been made to President Joe Biden’s and Vice President Kamala Harris’ protective details, Mayorkas said.

-ABC News’ Justin Ryan Gomez